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Amna Awan
12/3/2025
Biology
Introduction to the Skeletal System
188
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Dec 3, 2025
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Understanding the Skeletal System: Appendicular and Axial Structures
A
Amna Awan
@mnawan_qlyr
1 / 3
Introduction to the Skeletal System
Your skeletal system has two major divisions. The axial skeleton includes your skull (8 cranial and 14 facial bones), vertebral column (7 cervical, 12 thoracic, 5 lumbar vertebrae, plus the sacrum and coccyx), 12 pairs of ribs, sternum, hyoid bone, and ear ossicles. The appendicular skeleton contains all your limbs and their connections—shoulders, arms, hips, legs, hands, and feet.
The skeletal system serves five crucial functions. It enables movement by providing attachment points for muscles through tendons and ligaments. It creates a framework and support structure, with your backbone supporting your upper body. Your bones offer protection for vital organs—your skull shields your brain while ribs protect your heart and lungs.
Surprisingly, bones produce blood cells through tissue called marrow in their centers. Finally, bones act as a storage facility for minerals like calcium and phosphorus that your body needs.
Did you know? Every bone in your body serves at least one of these five functions, and many serve multiple purposes simultaneously!
Bone Classifications and Surface Features
Bones come in five distinct shapes, each designed for specific functions. Long bones like your femur and humerus are longer than wide with a shaft (diaphysis) and ends (epiphyses). Short bones are cube-shaped and found in your wrists (carpals) and ankles (tarsals). Flat bones like those in your skull are thin, usually curved, and have compact bone surrounding spongy bone inside.
Irregular bones don't fit other categories and include your vertebrae and hip bones. The fifth type, sesamoid bones like your kneecap (patella), are round and embedded in tendons.
Bone surfaces have specific features that serve important purposes. Projections grow outward and include rounded heads for forming joints, facets for connections, and condyles . Other projections serve as attachment points for muscles and tendons, like tuberosities and crests.
Quick tip: When studying bone markings, think of them as nature's puzzle pieces—each depression, hole, and projection helps bones connect perfectly with muscles, tendons, and other bones!
Skeletal Structure Overview
The axial skeleton forms your body's central structure. Your skull contains 8 cranial bones that protect your brain and 14 facial bones that shape your face. The vertebral column includes 7 cervical (neck), 12 thoracic (chest), and 5 lumbar (lower back) vertebrae, plus the sacrum and coccyx at the base. Your rib cage consists of 12 pairs of ribs, the sternum (breastbone), and costal cartilage.
The appendicular skeleton includes everything attached to your axial skeleton. Your upper portion starts with the pectoral girdle (clavicle and scapula), continues with the humerus in your upper arm, and the ulna and radius in your forearm. Your hands contain 8 carpals (wrist), 5 metacarpals (palm), and 14 phalanges (fingers).
Your lower portion begins with the pelvic girdle (ilium, pubis, and ischium), continues with the femur (thigh), and the tibia and fibula in your lower leg. Your feet contain 7 tarsals (ankles), 5 metatarsals (foot), and 14 phalanges (toes).
Connect the dots: Notice how your body has perfect symmetry—with identical numbers of bones on your left and right sides. This balance helps maintain proper posture and movement!
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This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
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Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
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I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
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Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
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In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
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I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Understanding the Skeletal System: Appendicular and Axial Structures
A
Amna Awan
@mnawan_qlyr
The skeletal system forms the framework of your body, giving you structure and enabling movement. This incredible system not only protects vital organs but also produces blood cells and stores important minerals your body needs to function properly.
Introduction to the Skeletal System
Your skeletal system has two major divisions. The axial skeleton includes your skull (8 cranial and 14 facial bones), vertebral column (7 cervical, 12 thoracic, 5 lumbar vertebrae, plus the sacrum and coccyx), 12 pairs of ribs, sternum, hyoid bone, and ear ossicles. The appendicular skeleton contains all your limbs and their connections—shoulders, arms, hips, legs, hands, and feet.
The skeletal system serves five crucial functions. It enables movement by providing attachment points for muscles through tendons and ligaments. It creates a framework and support structure, with your backbone supporting your upper body. Your bones offer protection for vital organs—your skull shields your brain while ribs protect your heart and lungs.
Surprisingly, bones produce blood cells through tissue called marrow in their centers. Finally, bones act as a storage facility for minerals like calcium and phosphorus that your body needs.
Did you know? Every bone in your body serves at least one of these five functions, and many serve multiple purposes simultaneously!
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Bone Classifications and Surface Features
Bones come in five distinct shapes, each designed for specific functions. Long bones like your femur and humerus are longer than wide with a shaft (diaphysis) and ends (epiphyses). Short bones are cube-shaped and found in your wrists (carpals) and ankles (tarsals). Flat bones like those in your skull are thin, usually curved, and have compact bone surrounding spongy bone inside.
Irregular bones don't fit other categories and include your vertebrae and hip bones. The fifth type, sesamoid bones like your kneecap (patella), are round and embedded in tendons.
Bone surfaces have specific features that serve important purposes. Projections grow outward and include rounded heads for forming joints, facets for connections, and condyles . Other projections serve as attachment points for muscles and tendons, like tuberosities and crests.
Quick tip: When studying bone markings, think of them as nature's puzzle pieces—each depression, hole, and projection helps bones connect perfectly with muscles, tendons, and other bones!
Sign up to see the contentIt's free!
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Skeletal Structure Overview
The axial skeleton forms your body's central structure. Your skull contains 8 cranial bones that protect your brain and 14 facial bones that shape your face. The vertebral column includes 7 cervical (neck), 12 thoracic (chest), and 5 lumbar (lower back) vertebrae, plus the sacrum and coccyx at the base. Your rib cage consists of 12 pairs of ribs, the sternum (breastbone), and costal cartilage.
The appendicular skeleton includes everything attached to your axial skeleton. Your upper portion starts with the pectoral girdle (clavicle and scapula), continues with the humerus in your upper arm, and the ulna and radius in your forearm. Your hands contain 8 carpals (wrist), 5 metacarpals (palm), and 14 phalanges (fingers).
Your lower portion begins with the pelvic girdle (ilium, pubis, and ischium), continues with the femur (thigh), and the tibia and fibula in your lower leg. Your feet contain 7 tarsals (ankles), 5 metatarsals (foot), and 14 phalanges (toes).
Connect the dots: Notice how your body has perfect symmetry—with identical numbers of bones on your left and right sides. This balance helps maintain proper posture and movement!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user